Trimming attachment for sewing machines



June 1964 J. E. HECKETHORN 3,135,229

TRIMMING ATTACHMENT FOR SEWING MACHINES Filed Aug. 14, 1961 2 Sheets-Sheet 1 H612 JOHN E.HECKETHORN* ATTORNE June 2, 1964 3,135,229

J. E HECKETHORN TRIMMING ATTACHMENT FOR SEWING MACHINES 2 Sheets-Sheet 2 Filed Aug. 14, 1961 FIG. 5 INVENTOR.

JOHN E. HECKET HORN ATTORNEY around 3,135,229 TRIMMING ATTACHMENT FOR SEWING MACHINES I John E. Heckethorn, Dyersburg, Tenn., assrgnor, by mesne assignments, to Heckethorn Manufacturing Co., Dyershurg, Tenn., a corporation of Colorado Filed Aug. 14, 1961, Ser. No. 131,210 Claims. (Cl. 112-124) This invention relates to a trimming attachment for sewing machines and has many uses. One of the principal uses is in the manufacture of seat cushions. In such manufacture, the upper and lower sheets of fabric, enclosing the cushioning material, are stitched together their peripheries. The two-stitched-together sheets are then trimmed to leave a protruding border area with its outer edge parallel to the line of stitching and a tape binding strip is folded over and stitched around the trimmed border area to cover and conceal the sheared edges. The trimming or shearing of the outer edge to provide a uniform border area is a tedious time-consuming manual task.

The principal object of this invention is to provide a border trimming attachment for a sewing machine which will continuously shear or trim the border edges of relatively heavy sheet materials simultaneously with the stitching operation so as to produce an accurate border area of uniform width completely about the article being stitched and which will require no attention on the part of the machine operator. Another object is to produce an attachment of this character which can be quickly removed from the machine When not desired and quickly replaced when needed and to provide such an attachment for the above purpose which will not interfere in any way with the interchange of bobbins or access to the operating mechanism of the sewing machine.

A still further object is to produce a border trimming attachment for sewing machines which can be fitted into the bobbin access opening in the base plate of a power sewing machine to replace the conventional bobbin cover plate of the machine and to provide an attachment which will not clutter up the working area of the machine and which can be simply lifted from place and swung aside for making bobbin changes.

Other objects and advantages reside in the detail construction of the invention, which is designed for simplicity, economy, and efiiciency. These will become more apparent from the following description.

In the followingdetailed description of the invention, reference is had to the accompanying drawing which forms a part hereof. Like numerals refer to like parts 1 ing machine upon which the attachment is mounted;

FIG. 2 is a horizontal section looking downwardly on the line 22, FIG. 1;

FIG. 3 is a detail left end view of the trimming attachment, per se;

FIG. 4 is a fragmentary longitudinal vertical section taken on the line 4-4, FIG. 3; and FIG. 5 is a perspective view of the trimmer removed from the sewing machine.

In the drawing, elements of a conventional power sewing machine are designated by numeral as follows: bed plate 11, supporting work table 12, pedestal 13, needle shaft 14, needle 15, foot 16 and drive belt 17. The bed plate 11 of such a machine is provided with rectangular access opening 18 for receiving a cover plate removal of United States Patent ner.

which gives access to the bobbin below the bed plate. This invention makes use of this access opening.

The attachment comprises a rectangular base plate 19 which fits into and completely closes the access opening 18 of the machine bed plate 11 and replaces the conventional bobbin cover plate. A backing plate 20 is aifixed to and arises from the inner edge of the base plate 19 to support a tubular cutter shaft housing 21. The inner extremity of the cutter shaft housing 21 is provided with a terminal flange 22 which is attached against the backing plate 20 in any suitable manner such as by means of suitable cap screws 23.

The cutter shaft housing is provided with two sets of ball bearings 24 in which a cutter shaft 25 is rotatably mounted. The outer extremity of the cutter shaft 25 has an enlarged head 26 against which an outwardly-bevelled, sharp-edged cutter disc 27 is clamped by means of a concentric clamp screw 28 The cutter disc has a beveled outer face and a flat inner face similar to a meat slicing blade and is prevented from rotating relative to the head 26 by means of a drive pin 29. The outer extremity of the cutter shaft housing 21 is formed with a semi-circular, flanged cutter guard 30 which surrounds the upper portion of the disc and prevents accidental contact therewith. A safety guard 31 is mounted on the front of the cutter guard 30 through the medium of suitable attachment screws 66. The screws 66 pass through vertically elongated screwholes in the guard 30 so that the latter may be adjusted vertically to a position for preventing the fingers of the operator from reaching the cutter disc. The safety guard 31 is provided with a finger 32 extend ing over the outer face of the cutter disc to prevent material from following the disc when the latter is rotating.

The inner face of the sharp edge of the cutter disc is positioned below and closely spaced relative to a hardened shear block 33 which is inset in a bottom block 34 fixedly mounted on the base plate 19. It can be seen that if the cutter disc be rotated downwardly as its forward edge, it will cooperate with the shear block 33 to exert a shearing action on material passing beneath the cutter disc. The exact cutting point of the cutting disc is displaced slightly forward of the line of needle penetration to permit accurate cutting around arcuate seam paths.

A U-shaped scrap chute 35 may, if desired, be secured to the rear edge of the backing plate 20 rearwardly of the cutter base 34 to receive the material sheared away by the cutter disc 27. The left vertical side of the scrap chute 35 would be aligned with the cutter disc so as to separate the trimmed scrap from the stitched articles.

The cutter shaft 25 maybe driven in any desired man- As illustrated, it is'driven from an electric motor 36 mounted on the front side of the pedestal 13. The motor 36 drives a drive shaft 37 extending through a tubular bearing spacer 38 in the pedestal 13. The bear ing spacer terminates in suitable anti-function bearings 39 whichin the embodiment illustrated are inset in counterboard recesses in the sides of the pedestal and in which the drive shaft is rotatably mounted. The outer extremity of the drive shaft terminates in a belt pulley 40 from which an endless drive belt 41 extends to a drive pulley 42 on the motor 36. The inner extremity of the drive shaft 37 terminates in a socket sleeve 43 provided with a bayonet slot 44. v

The cuttershaft 25 is connected to the drive shaft 37 by means of a flexible, extensible power transmission shaft assembly consisting of a first flexible, universal coupling .45, fitted over and mounted on the right extremity of the pling 51 connects rotating relative thereto by means of a key pin 49 which extends outwardly through an elongated key slot 5% in the sleeve 47. A second flexible, universal couthe extension shaft 48 with a stub shaft 52. The stub shaft 52-is designed to be slipped into the socket sleeve 43 and locked therein by means of a bayonet pin 53 engaged in the bayonet slot 44. The rotating shaft elements are shielded from accidental contacts by means of a cover plate 64 mounted at its one extremity on thetop of the backing plate 20, by means of suitable screws 65, and extending to the right over the flexible, extensible power transmission mechanism.

The backing plate 20 with all of the above connected elements is mounted for pivotal movements in a horizontal plane about the axis of a vertical pivot stub 54 extending upwardly from a mounting plate 55 fixedly mounted in the bed plate 11. The pivotal mounting is accomplished through the medium of a front pivot arm plate 56 which is secured at its left extremity to the backing plate 20, by means of suitable attachment screws 57, and which extends to the right from the latter. A pivot block 53 is fixedly mounted at the bottom of the right extremity of the pivot arm plate 56.. The pivot block has a vertical bore 59 adapted to be fitted over the pivot stud 54 so that the entire trimming attachment can be swung rearwardly in a horizontal plane about the axis of the pivot stud 54 when the base plate 19 is lifted from the bobbin access opening '18. It will be noted that when the attachment is swung rearwardly, such as to the broken line position of FIG. 2, the flexible shaft assembly will be fore shortened. This shortening is accommodated by the extension shaft portion 48 sliding with the sleeve 47 with the key pin 49 sliding along the key slot 50. i e

The front pivot arm plate 56 is provided with a finger grip tab 60 to facilitate lifting the base plate from the bobbin access opening 18 and to facilitate swinging the attachment rearwardly and back.

A switch plate 61 is mounted on the mounting plate 55 adjacent the pivot stud 54 and a push button switch 62 of the micro type is mounted below the switch late. ariety which, when an operating button 62' is depressed an electric circuit will be closed. The operating button 62' is positioned to be contacted by the pivot arm plate 56 to close a circuit when the attachment is swung to the operating position with its base plate in position in the bobbin access opening. The switch 62 is in circuit with the motor 36 so that whenever the attachment is swung rearwardly to change bobbins the motor will be automatically stopped. A conventional on and off switch 63 is also mounted on the switch plate 6t? for controlling the motor 36.

It is believed that the operation of the attachment will be apparent from the above description of the mechanism. Briefly, the material to be stitched, such as a seat cushion, is fed beneath the needle in the customary manner.

The switch 62 is of any conventional press button 7 The edges of thesheets will travel beneath the rapidly rotating cutter disc 27 and will be uniformly trimmed 'as the needle travels along the seam thus maintaining an accurate uniform border corresponding in width to the preset distance between the needle and the disc.

When the bobbin change is necessary, the operator simply grasps the finger tab 60, lifts the base plate 19 from the bobbin access opening 18 and swings the entire attachment rearwardly, as indicated in broken line in FIG. 2, to allow full access to the bobbin compartment. The swinging of the attachment to provide access requires less time than the removal and replacement of the conventional bobbin cover plate so that bobbin change is not only not interfered with but is actually facilitated.

It is often necessary for repairs, cleaning, oiling, etc. to tilt the entire bed plate of the machine. The attachment in no way interferes with this procedure for since the motor is mounted on the pedestal 13 and the remainder is mounted on the bed plate 111, the entire attachment will follow the rearward tilt of the machine without interference.

Should the sewing machine be desired for other uses the stub shaft 52 can be quickly detached from the bayonet slotted sleeve 43 so that the entire trimming attachment can be simply lifted and removed from the bed plate of the machine. To replace it, it is only ecessary to slide the pivot block 58 down over the pivot stud 54 and replace the stub shaft 52 in the bayonetslotted sleeve 43.

It is very important that the included angle between the cutting disc and the carbide cutting plate be kept as low as possible. In other words, the cutting disc must barely overlap the top surface of the cutting plate, creating a very low included angle between these members, which provides a pulling action and reduces the force required to feed the cloth into the cutter to near zero.

While the drive shaft 37 has been illustrated as journalled in the sewing machine pedestal 13 as a matter of convenience, any other type of suitable offset drive from the motor 36 could be employed or the pulley 44) could be driven directly by contact with the sewing machine drive belt 17 if preferred.

The cutter shaft housing flange 22 of the cutter shaft housing 21 is positioned upon the backing plate 20 so as to obtain the proper overlap between the disc and the shear block 33.

The cutter base block 34 can also be adjusted forward back to obtain the proper cutting action on the material being stitched'by loosening a base block attachment screw 67 and sliding it along an elongated, flanged screw slot 68 in the base plate 19.

While a specific form of the improvement has been described and illustrated herein, it is to be understood that the same may be varied within the scope of the appended claims, without departing from the spirit of the invention.

Having thus described the invention what is claimed and desired to be secured by Letters Patent is:

l. The combination with the bed plate of a sewing machine, of a type having a bobbin access opening in the bed plate, of a base plate fitted into and closing said access opening, an edge trimming attachment mountedon said base plate for trimming the edges of material being stitched onsaidmachine, and a vertical pivot element afiixed on said bed plate; a pivot arm extending from said base plate, said pivot arm being mounted on said pivot element for both vertical and rotative move- -ment so that said base plate may be lifted from and swung horizontally away from said opening.

2. An edge trimming attachment adapted to be mounted on the bed plate of a sewing machine, for trimming the edges of materials being stitched by the needle of said machine, comprising: a base plate; a bearing support mounted on said base plate; shaft bearings supported from said support; a horizontal cutter disc shaft rotatably supported in said bearings; a'cutter disc mounted on said shaft adjacent said needle; means for transmitting rotation to said cutter shaft; avpivot arm extend ing from said bearing support over said bed'plate; and

' a vertical axis pivot means pivoting the extremity of said pivot arm to said bed plate so that said base plate may 'be. swung'in a horizontal plane to and from;said opening.

when said base plate is swung from said opening said switch will be actuated by said arm to open the circuit to said motor.

5. An edge trimming attachment for a sewing machine of a type having a bed plate with a bobbin access opening therein comprising: a base plate of a shape and size to fit into and close the access opening, said opening preventing horizontal shifting of said base plate; a vertical backing plate aifixed to and arising from the inner edge of said base plate; a tubular shaft bearing housing mounted on said backing plate and extending horizontally over said base plate; a horizontal cutter shaft rotatably mounted in siad bearing housing and extending at its inner extremity through said backing plate; a cutter disc i mounted on the outer extremity of said shaft; a bottom block fixedly mounted on said base plate; a shear block positioned on said bottom block in shearing relation to 'said cutter disc; power transmission means connected to the inner extremity of said shaft for rotating the latter;

a front pivot arm attached to said backing plate at its one extremity and extending horizontally therefrom; a

vertical pivot stud extending upwardly from said bed plate; and pivot stud engaging means on the other extremity of said front pivot arm, said pivot stud engaging means being both vertically and rotatably movable on said pivot stud so that said base plate may be lifted from and swung to one side of said access opening.

References (Iited in the file of this patent UNITED STATES PATENTS Weis Feb. 21, 1939 

1. THE COMBINATION WITH THE BED PLATE OF A SEWING MACHINE, OF A TYPE HAVING A BOBBIN ACCESS OPENING IN THE BED PLATE, OF A BASE PLATE FITTED INTO AND CLOSING SAID ACCESS OPENING, AN EDGE TRIMMING ATTACHMENT MOUNTED ON SAID BASE PLATE FOR TRIMMING THE EDGES OF MATERIAL BEING STICHED ON SAID MACHINE, AND A VERTICAL PIVOT ELEMENT AFFIXED ON SAID BED PLATE; A PIVOT ARM EXTENDING FROM SAID BASE PLATE, SAID PIVOT ARM BEING MOUNTED ON SAID PIVOT ELEMENT FOR BOTH VERTICAL AND ROTATIVE MOVEMENT SO THAT SAID BASE PLATE MAY BE LIFTED FROM AND SWUNG HORIZONTALLY AWAY FROM SAID OPENING. 